Nitrogen oxides, nitric oxide and/or other nitrogen oxide gases have, in the past, been essentially discharged with waste gases into the atmosphere. The industrial activities creating these gases, which may no longer be discharged in such quantity because of today's air pollution standards, include, for example, the production of nitric acid, cleaning, pickling, and/or dissolving of metals, decomposition of nitrates and other nitrogen containing materials, and subjecting mixtures of oxygen and nitrogen to high temperatures. There are some existing nitrogen oxides recovery processes now being used to reduce or eliminate the nitrogen oxides in waste gas streams prior to their discharge and they are described as follows: